1. Field of the Invention
The present invention relates to a thermal transfer sheet and an image formation method using it.
2. Description of the Related Art
Recently, a dye diffusion transfer recording system has become specifically noted as a process capable of producing color hard copies of which the image quality is the nearest to that of silver salt photographs. Moreover, as compared with silver salt photographs, the system has other various advantages in that it is a dry system, it can produce visible images directly from digital data, it is simple in image duplication, and the system for image formation can be constructed relatively inexpensively.
In the dye diffusion transfer recording system, a dye (or colorant)-containing thermal transfer sheet and a thermal transfer image-receiving sheet (hereinafter this may be simply referred to as “image-receiving sheet”) are put one upon another, and the thermal transfer sheet is heated with a heating element such as thermal head from which the heat generation is controlled by electric signals given thereto, whereby the dye in the thermal transfer sheet is transferred onto the image-receiving sheet for image information recording thereon. In this, three colors of cyan, magenta and yellow, or four colors of these and black are recorded as superimposed, thereby giving a color image having a continuously changing color density in a mode of transfer recording.
JP-A 2003-205686 discloses a thermal transfer sheet containing a pyrazolonemethine-type yellow dye having a specific structure.
JP-A 2006-116892 discloses a thermal transfer sheet containing, in the subbing layer thereof, inorganic fine particles of colloidal silica or colloidal alumina.
On the other hand, recently, dye diffusion transfer recording systems have become much popularized and have become driven at a higher speed, and they have become installed in amusement parks, sightseeing spots and the like for application to real-time printing.
However, in outputting prints from conventional dye diffusion transfer recording systems installed in amusement parks or sightseeing spots, there often occur some troubles of panel failure and at worst system down.
The present inventors investigated the troubles with conventional dye diffusion transfer recording systems, and have known that, inside the troubled printers, a severe environmental cycle of high-temperature and low-humidity in daytime and low-temperature and high-humidity in nighttime is repeated, and with the lapse of time, the environmental change cycles after all have some negative influences on the runnability of the thermal transfer sheet charged inside the printer in the form of a roll, during image formation thereon.